Gas-sensing properties and mechanism of Pd-GaNNTs for air decomposition products in ring main unit

Abstract

Ring main unit acts as an important role in modern power transmission and distribution systems. Partial electric discharge frequently occurs in ring main unit because of insulation faults. Along with the partial electric discharge, the air filled in ring main unit decomposes to various decomposition products, where NO, CO, O3, N2O4 are the characteristic products. This work devotes to detect the partial electric discharge by detecting these four characteristic gases. Based on first-principle calculation, Pd-modified gallium nitride nanotubes (Pd-GaNNTs) was proposed as a novel gas sensor for these gases detection. Pd atom doping greatly enhances the surface activity of GaNNTs. Gas-sensing properties and mechanism of Pd-GaNNTs to these four characteristic gases were analyzed based on adsorption energy, charge transfer amount, total density of states, projected density of states, and the molecular orbits calculations. The adsorption stability of Pd-GaNNTs to these gases ranked as: N2O4 > CO > O3 > NO, and the effect of gas adsorption on the conductivity is: O3 > NO > N2O4 > CO. Calculation results show that Pd-GaNNTs could be a promising material to prepare new generation gas sensor using in partial electric discharge detection in ring main unit.